The formula with 5 substituted
miles = 5 ÷ 1.609344 = 3.107
The constant is an exact definition, not a rounded factor: the mile is 1.609344 km, the US gallon is 3.785411784 litres and the imperial gallon is 4.54609 litres. The Kilometres to Miles Converter explains where each comes from and gives a longer table.
At a walking pace of 5 km/h, 5 km takes about 60 minutes. At an easy running pace of 10 km/h it takes about 30. In metres it is 5,000.
What 5 kilometres means in practice
5 km is the most-run distance in the world, 3.107 miles, the parkrun and fun run standard. Twelve and a half laps of a track. A walker needs about an hour; a first-time runner 30 to 40 minutes; the world record is a little over 12.